(a) Field of the Invention
The present invention relates to a liquid crystal display and, more particularly, to a color filter substrate for a liquid crystal display.
(b) Description of the Related Art
Generally, liquid crystal displays have a structure where a liquid crystal is sandwiched between two substrates, and an electric field is applied to the liquid crystal to control light transmission. Among the substrates, the bottom substrate is provided with thin film transistors and pixel electrodes, and usually called the “thin film transistor array substrate.” The top substrate is provided with a common electrode and color filters, and usually called the “color filter substrate.”
In order to fabricate such a liquid crystal display at a lower cost within reduced time period, it is necessary to simplify the photolithography process that involves complicated processing steps.
FIGS. 1A through 1D sequentially illustrate the steps of fabricating a color filter substrate for a liquid crystal display according to a prior art.
As shown in FIG. 1A, a chrome oxide layer 21 and a chrome layer 22 are sequentially deposited onto a transparent glass substrate 10, and patterned through photolithography to thereby form a black matrix 20.
As shown in FIG. 1B, color filters 30 of red, green and blue colors are formed on the substrate 10 with the black matrix 20 though performing photography three times. In the photography process, a layer based on a photosensitive material containing pigment is deposited onto the substrate 10, exposed to light, and developed.
As shown in FIG. 1C, a common electrode 40 is formed on the color filters 30 with a transparent conductive material such as indium tin oxide (ITO).
In the case of twisted nematic (TN) mode liquid crystal displays, the color filter substrate is completed through the above processing steps. That is, the color filter substrate is fabricated through performing photolithography one time, and photography three times.
However, in case opening portions are formed at the common electrode and the pixel electrodes to obtain wide viewing angle characteristic with a patterned vertically aligned (PVA) mode, an additional process of photolithography should be introduced. That is, as shown in FIG. 1D, opening portions 41 are formed at the common electrode 40 through photolithography.
Furthermore, when the opening portions 41 are formed at the common electrode 40, the color filters 30 suffer damages during the etching process while being exposed through the opening portions 41, and this deteriorates the property of the liquid crystal.
In order to solve such problems, it has been suggested that protrusions based on an organic material should be formed at the common electrode 40 instead of the opening portions 41, or opening portions and protrusions should be formed only at the pixel electrodes without patterning the common electrode 40. However, such techniques yet involve complicated processing steps and does not provide sufficient wide viewing angle.